title: Connectivity within the primary motor cortex: a DTI tractography study.
abstract: OBJECTIVE
  Because of the motor function of the precentral area, the connections of the primary motor cortex by white matter fiber bundles have been widely studied in diffusion tensor imaging (DTI). Nevertheless, the connections within the primary motor cortex have yet to be explored. We have studied the connectivity between the different regions of the precentral gyrus in a population of subjects.
  
  
  METHODS
  Based on T1 magnetic resonance imaging (MRI) and on individual sulco-gyral anatomy, we defined a parcellation of the right and the left precentral gyri in 20 healthy subjects (10 right-handers; 10 left-handers). This parcellation gave us the opportunity to study MRI tracks reconstructed by tractography within the precentral gyrus and to compare these connections across subjects. We also performed a classical dissection of post-mortem brain tissue to isolate this pattern of connectivity.
  
  
  RESULTS
  We showed MRI tracks connecting the different parts of the same precentral gyrus. This result was reproducible and was found in the left and right hemispheres of the 20 subjects. A quantitative description of the bilateral distribution of the MRI tracks was performed, based on statistical analysis and asymmetry indices, to compare asymmetry and handedness.
  
  
  CONCLUSIONS
  To the best of our knowledge, this pattern of connectivity has never before been detailed in the literature. Its functional meaning remains to be determined, which requires further study.
authors.affiliation: Service de Neurochirurgie, CHRU Cavale Blanche, 29200, Brest, France, elsa.magro@chu-brest.fr.
authors.forename: Elsa
authors.initials: E
authors.lastname: Magro
authors.forename: Tristan
authors.initials: T
authors.lastname: Moreau
authors.forename: Romuald
authors.initials: R
authors.lastname: Seizeur
authors.forename: Ilyess
authors.initials: I
authors.lastname: Zemmoura
authors.forename: Bernard
authors.initials: B
authors.lastname: Gibaud
authors.forename: Xavier
authors.initials: X
authors.lastname: Morandi
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D009044:Motor Cortex / Q000033:anatomy & histology*; D009434:Neural Pathways / Q000033:anatomy & histology*; D012016:Reference Values; D055815:Young Adult